If an effect allows you to cast a spell with tiered "without paying its mana cost," you must still choose exactly one mode and pay the associated additional cost
I recently got back into playing Magic after about 15 years, and Im happy that my current more-mathematically minded brain is finding many ways of analysing the game (so expect more posts on this in the near future)
Illustrated by Greg Hildebrandt Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Not Legal Modern Legal Brawl Not Legal Legacy Legal Comp
This has the potential to create a formidable snowball effect where your spells become increasingly massive as the game progresses

Decklist: Ayula, Queen Among Bears in Commander Wilson, Refined Grizzly | Illustration by Ilse Gort Commander (1) Planeswalker (1) Creature (32) Adaptive Automaton Alpine Grizzly Ashcoat Bear Balduvian Bears Bear Cub Beast Whisperer Bosco, Just a Bear Caller of the Claw Copper Host Crusher Dragon-Scarred Bear Drover Grizzly Druid's Familiar Evercoat Ursine Goreclaw, Terror of Qal Sisma Grizzly Bears Lumra, Bellow of the Woods Masked Vandal Mother Bear Owlbear Owlbear Cub Rampaging Yao Guai Realmwalker River Bear Runeclaw Bear Ruxa, Patient Professor Spider-Ham, Peter Porker Striped Bears Surrak and Goreclaw The Earth King Ursine Monstrosity Werebear Wilson, Refined Grizzly Instant (7) Archdruid's Charm Beast Within Heroic Intervention Inspiring Call Krosan Grip Return of the Wildspeaker Return to Nature Sorcery (9) Cultivate Fade from History Grizzly Fate Harmonize Kamahl's Summons Kodama's Reach Rampant Growth Shamanic Revelation Titania's Command Enchantment (9) Ayula's Influence Bear Umbra Bearscape Beastmaster Ascension Hardened Scales Sylvan Anthem Tribute to the World Tree Unnatural Growth Words of Wilding Artifact (8) Emerald Medallion Lifecrafter's Bestiary Panharmonicon Patchwork Banner Rhonas's Monument Sol Ring Swiftfoot Boots Vanquisher's Banner Land (33) Argoth, Sanctum of Nature Castle Garenbrig Forest x26 Mosswort Bridge Oran-Rief, the Vastwood Path of Ancestry Rogue's Passage Three Tree City Ayula, Queen Among Bears is my pick for a bear typal deck in Commander

That said, using creatures to Station is far faster, as one Charge Counter per turn doesnt amount to much